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Abstract:

There are provided a transparent panel and a method of manufacturing the
same. The transparent panel includes a transparent substrate; and a
transparent electrode layer formed on the transparent substrate, wherein
the transparent electrode layer includes a first area having
non-electrical conductivity and a second area having electrical
conductivity, and the first area includes a graphene oxide, and the
second area includes a reduced graphene oxide. Accordingly, a sensing
electrode may be formed without a step to thereby minimize a pattern
exposure phenomenon, and the manufacturing process may be simplified.

Claims:

1. A transparent panel, comprising: a transparent substrate; and a
transparent electrode layer formed on the transparent substrate, wherein
the transparent electrode layer includes a first area having
non-electrical conductivity and a second area having electrical
conductivity, and the first area includes a graphene oxide, and the
second area includes a reduced graphene oxide.

2. The transparent panel of claim 1, wherein the transparent electrode
layer has the same thickness in the first area and the second area.

3. The transparent panel of claim 1, wherein the transparent substrate is
a cover lens receiving a touch applied to at least one surface thereof.

5. A method of manufacturing a transparent panel, the method comprising:
preparing a transparent substrate; forming a graphene oxide layer on the
transparent substrate; providing an etching resist on a first area
corresponding to a portion of the graphene oxide layer; and reducing a
second area of the graphene oxide layer other than the first area.

6. The method of claim 5, wherein the etching resist has acid resistance.

7. The method of claim 5, wherein the reducing of the second area
comprises reducing the second area using a gaseous or liquid reducing
agent including at least one of iodic acid (HI), ammonia (NH3),
sodium hydroxide (NaOH), potassium hydroxide (KOH), hydrogen sulfide,
hydrazine, and aluminum powder.

8. The method of claim 5, wherein the providing of the etching resist is
performed by forming a photoresist on the first area.

9. The method of claim 5, wherein the providing of the etching resist is
performed by laminating a dry film resist (DFR) on the first area.

10. The method of claim 5, wherein the forming of the graphene oxide
layer is performed by at least one of a gravure coating method, a slot
die coating method, and a spray coating method.

11. The method of claim 5, further comprising removing the etching resist
from the first area.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the priority of Korean Patent Application
No. 10-2011-0136355 filed on Dec. 16, 2011 in the Korean Intellectual
Property Office, the disclosure of which is incorporated herein by
reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a transparent panel in which a
transparent electrode is formed on a surface of a transparent substrate
without a step, to minimize a pattern exposure phenomenon and simplify
the manufacturing process thereof, and a method of manufacturing the
transparent panel.

[0004] 2. Description of the Related Art

[0005] A transparent panel is a device manufactured by forming an
electrode having a predetermined pattern using a transparent conductive
material having excellent light transmittance on a transparent substrate
having excellent light transmittance. The transparent panel is widely
used in flat panel displays (FPDs) such as a liquid crystal display (LCD)
or an organic light emitting display (OLED) or an input device such as a
touch screen. In particular, flat panel displays are currently provided
as televisions for the home, and users of devices such as smartphones and
navigation devices including a touch screen as an input device are
increasing, such that demand for transparent panels is also increasing.

[0006] Methods of sensing a touch screen contact applied to electronic
devices may be classified as a resistive method and a capacitive method.
The capacitive method allows for a relatively long lifespan, and various
types of intuitive input methods, and ease of movements during touch
contact, and thus is increasingly being applied to electronic devices. In
particular, as compared to the resistive method, it is easy to implement
a multi-touch interface in the capacitive method, and thus it is being
widely used in devices such as smartphones.

[0007] Touch screens using both the resistive method and the capacitive
method include a transparent substrate and a transparent electrode formed
on a surface of the transparent substrate. The transparent electrode may
be formed by depositing a transparent conductive material such as
indium-tin oxide (ITO), zinc oxide (ZnO), or indium-zinc oxide (IZO) on
the surface of the transparent substrate using a sputtering method or the
like, and etching the deposited transparent conductive material to have a
desired pattern. However, in this case, there are provided an area in
which the transparent conductive material is formed and an area in which
the transparent conductive material is removed on the surface of the
transparent substrate, and thus, a pattern exposure phenomenon may be
generated due to a difference in light transmittance and refractive
indices between the transparent electrode and the transparent substrate.

SUMMARY OF THE INVENTION

[0008] An aspect of the present invention provides a transparent panel in
which a transparent electrode is formed without a step by forming a
graphene oxide layer on a transparent substrate, forming an etching
resist on a first area which is at least a portion of the graphene oxide
layer, and then reducing a second area, apart from the first area, such
that the second area may obtain electrical conductivity. Thus, a pattern
exposure phenomenon may be minimized, and the manufacturing process of
the transparent panel may be simplified.

[0009] According to an aspect of the present invention, there is provided
a transparent panel, including: a transparent substrate; and a
transparent electrode layer formed on the transparent substrate, wherein
the transparent electrode layer includes a first area having
non-electrical conductivity and a second area having electrical
conductivity, and the first area includes a graphene oxide, and the
second area includes a reduced graphene oxide.

[0010] The transparent electrode may have the same thickness in the first
area and the second area.

[0011] The transparent substrate may be a cover lens receiving a touch
applied to at least one surface thereof.

[0012] The transparent substrate may include at least one of tempered
glass, polycarbonate (PC), polyimide (PI), polyethylene terephthalate
(PET), and polymethymethacrylate (PMMA).

[0013] According to another aspect of the present invention, there is
provided a method of manufacturing a transparent panel, the method
including: preparing a transparent panel; forming a graphene oxide layer
on the transparent panel; providing an etching resist on a first area
corresponding to a portion of the graphene oxide layer; and reducing a
second area of the graphene oxide layer other than the first area.

[0014] The etching resist may have acid resistance.

[0015] The reducing of the second area may include reducing the second
area using a gaseous or liquid reducing agent including at least one of
iodic acid (HI), ammonia (NH3), sodium hydroxide (NaOH), potassium
hydroxide (KOH), hydrogen sulfide, hydrazine, and aluminum powder.

[0016] The providing of the etching resist may be performed by forming a
photoresist on the first area.

[0017] The providing of the etching resist may be performed by laminating
a dry film resist (DFR) on the first area.

[0018] The forming of the graphene oxide layer may be performed by at
least one of a gravure coating method, a slot die coating method, and a
spray coating method.

[0019] The method may further include removing the etching resist from the
first area.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and other aspects, features and other advantages of the
present invention will be more clearly understood from the following
detailed description taken in conjunction with the accompanying drawings,
in which:

[0021] FIG. 1 is a perspective view of an exterior of an electronic device
including a transparent panel according to an embodiment of the present
invention;

[0022] FIG. 2 illustrates a touch screen including a transparent panel
according to an embodiment of the present invention;

[0024] FIG. 4 is a flowchart illustrating a method of manufacturing a
transparent panel according to an embodiment of the present invention;
and

[0025] FIG. 5 is a schematic view for explaining a method of manufacturing
a transparent panel according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Embodiments of the present invention will be described in detail
with reference to the accompanying drawings. These embodiments will be
described in detail in order to allow those skilled in the art to
practice the present invention. It should be appreciated that various
embodiments of the present invention are different but are not
necessarily exclusive. For example, specific shapes, configurations, and
characteristics described in an embodiment of the present invention may
be implemented in another embodiment without departing from the spirit
and scope of the present invention. In addition, it should be understood
that positions and arrangements of individual components in each
embodiment may be changed without departing from the spirit and scope of
the present invention. Therefore, a detailed description provided below
should not be construed as being restrictive. In addition, the scope of
the present invention is defined only by the accompanying claims and
their equivalents if appropriate. Similar reference numerals will be used
to describe the same or similar functions throughout the accompanying
drawing.

[0027] Hereinafter, embodiments of the present invention will be described
in detail with reference to the accompanying drawings so that those
skilled in the art may easily practice the present invention.

[0028] FIG. 1 is a perspective view of an exterior of an electronic device
to which a touch sensing device according to an embodiment of the present
invention is applicable. Referring to FIG. 1, an electronic device 100
according to the present embodiment of the invention may include a
display device 110 for outputting an image, an input unit 120, an audio
unit 130 for outputting audio, and a touch sensing device integrated with
the display device 110. In this case, a transparent panel according to an
embodiment of the present invention may be applied not only to the
display device 110 but also to a touch screen-type touch sensing device.

[0029] As illustrated in FIG. 1, in the case of a mobile apparatus, the
touch sensing device is generally provided integrally with the display
device and needs to have high light transmittance enough to transmit the
image displayed by the display device. Accordingly, the touch sensing
device may be implemented by forming a sensing electrode using a
transparent and electrically conductive material such as indium-tin oxide
(ITO), indium zinc oxide (IZO), zinc oxide (ZnO), carbon nano tube (CNT),
or graphene, on a base substrate formed of a transparent film material
such as polyethylene terephthalate (PET), polycarbonate (PC),
polyethersulfone (PES), polyimide (PI), or the like. The display device
may include a wiring pattern disposed in a bezel area thereof, and the
wiring pattern is connected to the sensing electrode formed of the
transparent conductive material. Since the wiring pattern is visually
shielded by the bezel area, the wiring pattern may be formed of a
metallic material such as silver (Ag), copper (Cu), or the like.

[0030] The transparent panel according to the present embodiment may be
formed by forming a graphene oxide layer on at least a surface of a
transparent substrate and selectively reducing only a portion of the
graphene oxide. The graphene oxide may be mixed with water or an organic
solvent and be easily applied to at least one surface of the transparent
substrate in the form of a dispersion solution. As the graphene oxide has
electrical conductivity only in the selectively reduced portion, it may
function as a transparent electrode.

[0031] Hereinafter, for convenience of explanation, description will be
provided by assuming that the transparent panel according to the present
embodiment is applied to a touch screen. However, the description does
not limit the applications of the transparent panel, and the transparent
panel according to the present embodiment may also be applied to various
devices other than touch screens.

[0032] FIG. 2 illustrates a touch screen including a transparent panel
according to an embodiment of the present invention. A touch screen 200
illustrated in FIG. 2 includes a transparent substrate 210 and a
plurality of sensing electrodes 220 and 230 formed on the transparent
substrate 210. The plurality of sensing electrodes 220 and 230 may
include first electrodes 220 for sensing a touch in a Y-axis direction
and second electrodes 230 for sensing a touch in an X-axis direction.
Referring to FIG. 2, it is assumed that the eight first electrodes 220
and the eight second electrodes 230 are provided and the first electrodes
220 and the second electrodes 230 are connected to sensing channels Y1 to
Y8 and X1 to X8 of a controller chip, respectively.

[0033] Referring to FIG. 2, the first electrodes 220 and the second
electrodes 230 are illustrated as being formed on the same plane of the
transparent substrate 210 for convenience of illustration; however, the
first electrodes 220 and the second electrodes 230 may also be formed
separately on upper and lower surfaces of the transparent substrate 210,
or on a plurality of transparent substrates 210. That is, the touch
screen 200 of FIG. 2 is merely an example for describing the transparent
panel according to the embodiment of the present invention, and the
transparent panel according to the present embodiment may also be
included in touch screens having different structures from that of the
touch screen 200 illustrated in FIG. 2.

[0034] Referring to FIG. 2, the plurality of sensing electrodes 220 and
230 are formed on the transparent substrate 210, and the sensing
electrodes 220 and 230 are patterned such that predetermined shapes are
repeated. Referring to FIG. 2, the sensing electrodes 220 and 230 are
patterned such that the unit electrodes having a rhombus or
diamond-shaped pattern are continuously connected to one another in the
X-axis or Y-axis direction. According to the present embodiment of the
invention, a graphene oxide layer is formed on a surface of the
transparent substrate 210, and a portion of the graphene oxide layer is
reduced by using a gaseous or liquid reducing agent to allow for
electrical conductivity, whereby the sensing electrodes 220 and 230
having the pattern illustrated in FIG. 2 may be formed.

[0035] As shown in FIG. 2, the first electrodes 220 for sensing the
position of the touch on the Y-axis and the second electrodes 230 for
sensing the position of the touch on the X-axis may be arranged such that
the plurality of the second electrodes 230 fill empty areas between the
plurality of first electrodes 220 and the plurality of first electrodes
220 fill empty areas between the plurality of second electrodes 230.
Thus, a first graphene oxide layer used to form the plurality of first
electrodes 220 is reduced with the exception of areas thereof in which
the plurality of second electrodes 230 are formed, thereby obtaining
electrical conductivity. On the other hand, a second graphene oxide layer
used to form the plurality of second electrodes 230 is reduced with the
exception of areas thereof in which the plurality of first electrodes 220
are formed, thereby obtaining electrical conductivity.

[0036] In general, in a device including a transparent panel such as a
touch screen, transparent electrodes are formed on a transparent
substrate by forming a transparent conductive material on a surface of
the transparent substrate by sputtering, and then removing the
transparent conductive material therefrom, with the exception of portions
thereof allowing for a desired shape (pattern), by etching. However, in
this case, steps are necessarily formed between the transparent
electrodes and the portions in which the transparent electrodes are not
formed by the etching process of removing the transparent conductive
material. Here, an area of the transparent substrate from which the
transparent electrodes are removed may be damaged by a chemical etching
process. Further, in the case in which the transparent electrodes may not
be properly removed in the etching process, and problems such as a short
circuit between the electrodes, which are to be electrically separated
from each other, may occur.

[0037] FIGS. 3A and 3B are cross-sectional views of the touch screen of
FIG. 2. FIG. 3A is a cross-sectional view of a touch screen using a
transparent panel manufactured by a general manufacturing method, and
FIG. 3B is a cross-sectional view of a touch screen using a transparent
panel according to an embodiment of the present invention.

[0038] Referring to FIG. 3A, a cover lens 340a, a first transparent
adhesive layer 360a, a first transparent substrate 313a, a second
transparent adhesive layer 370a, a second transparent substrate 315a, a
gasket adhesive portion 380a, and a display device 350a are sequentially
stacked. First and second sensing electrodes 320a and 330a are formed on
the first and second transparent substrates 313a and 315a, respectively,
thereby forming first and second transparent panels. The first and second
transparent adhesive layers 360a and 370a may have excellent light
transmittance such as an optical clear adhesive (OCA).

[0039] The display device 350a may be a flat panel display device but is
not limited thereto. The display device 350a is attached to a lower
substrate of a touch screen--the second transparent substrate 315a of
FIG. 3A--using the gasket adhesive portion 380a or the like. The gasket
adhesive portion 380a may be disposed at edges of the display device
350a, and an air gap is formed in an area in which the gasket adhesive
portion 380a is not provided, between the display device 350a and the
second transparent substrate 315a. The air gap may alleviate a phenomenon
that electrical noise generated in the display device 350a is transmitted
to the first and second sensing electrodes 320a and 330a to hinder the
determination of the touch.

[0040] In the touch screen of FIG. 3A, the first and second sensing
electrodes 320a and 330a formed on the first and second transparent
substrates 313a and 315a may be formed of a transparent conductive
material such as ITO, IZO, or ZnO. Also, as illustrated in FIG. 3A, the
transparent conductive material is completely removed, using an etching
process or the like, with the exception of an area in which the first and
second sensing electrodes 320a and 330a are to be formed. Thus, a
difference in thickness between the area in which the first and second
sensing electrodes 320a and 330a are formed and the remaining area, that
is, a step is generated.

[0041] The step between the first and second sensing electrodes 320a and
330a and the first and second transparent substrates 313a and 315a may
increase a failure rate of a manufacturing process or may increase the
possibility of the pattern exposure phenomenon of the first and second
sensing electrodes 320a and 330a. It is known that the pattern exposure
phenomenon of the first and second sensing electrodes 320a and 330a due
to the step may be alleviated by the first and second adhesive layers
360a and 370a. However, in the case of a window-integrated touch screen
in which the sensing electrodes 320a and 330a are directly formed on a
surface of the cover lens 340a, additional transparent adhesive layers
360a and 370a are not disposed between the cover lens 340a and the
sensing electrodes 320a and 330a, and thus it is difficult to prevent the
pattern exposure phenomenon.

[0042] In addition, in a chemical etching process for forming the first
and second sensing electrodes 320a and 330a, the remaining area of the
first and second transparent substrates 313a and 315a in which the first
and second sensing electrodes 320a and 330a are not formed may be damaged
physically or chemically. This may cause scratches on the surfaces of the
first and second transparent substrates 313a and 315a to increase a haze,
thereby deteriorating transmittance and intensifying the pattern exposure
phenomenon of the first and second sensing electrodes 320a and 330a.

[0043] FIG. 3B is a cross-sectional view of a stack structure of a touch
screen to which a transparent panel according to an embodiment of the
present invention is applied. Referring to FIG. 3B, a cover lens 340b, a
first transparent adhesive layer 360b, a first transparent substrate
313b, a second transparent adhesive layer 370b, a second transparent
substrate 315b, a gasket adhesive portion 380b, and a display device 350b
are sequentially stacked. The stacking order is similar to that of FIG.
3A, except that first and second sensing electrodes 320b and 330b are
respectively formed on first and second transparent substrates 313b and
315b without a step.

[0044] A graphene oxide layer is formed on the separate first and second
transparent substrates 313b and 315b by applying a graphene oxide a spray
coating method, a slot die coating method, a gravure coating method or
the like, and an etching resist is only formed on first areas 325b and
335b corresponding to portions of the graphene oxide layer. A graphene
oxide refers to a liquid insulation solution prepared by melting a
solid-type graphite material in water or other organic solvent. The
graphene oxide has excellent dispersibility, and thus may be easily
applied to the first and second transparent substrates 313b and 315b.

[0045] When the etching resist is formed on the first areas 325b and 335b
of the graphene oxide layer, the entirety of the graphene oxide layer is
reduced using a predetermined reducing agent. Examples of the reducing
agent include at least one of iodic acid, ammonia (NH3), sodium
hydroxide (NaOH), potassium hydroxide (KOH), hydrogen sulfide, hydrazine,
and aluminum powder. The etching resist function as a shield so that the
first areas 325b and 335b of the graphene oxide layer are not reduced by
the reducing agent, and thus the etching resist may be formed of a
material having acid resistance so as not to be melted by acid.

[0046] By reducing the graphene oxide layer, on which the etching resist
is formed, using a reducing agent, the first areas 325b and 335b blocked
from being in contact with the reducing agent due to the etching resist
may have non-electrical conductivity as the properties of the graphene
oxide. On the other hand, second areas, that is, the remaining areas with
the exception of the first areas 325b and 335b, are reduced by the
reducing agent to thereby obtain electrical conductivity. Accordingly,
the first and second sensing electrodes 320b and 330b are formed in the
second areas by a reduction process without a chemical etching or washing
process. Also, no step is formed between the second areas having
electrical conductivity in which the first and second sensing electrodes
320b and 330b are formed and the first areas 325b and 335b having
non-electrical conductivity, as illustrated in FIG. 3B.

[0047] That is, the graphene oxide is formed on the first and second
transparent substrates 313b and 315b regardless of whether they have
electrical conductivity or non-electrical conductivity. Thus, compared to
the embodiment illustrated in FIG. 3A, a difference between a refractive
index of the second areas in which the first and second sensing
electrodes 320b and 330b are formed and a refractive index of the first
areas 325b and 335b having non-electrical conductivity is decreased.
Consequently, the pattern exposure phenomenon of the first and second
sensing electrodes 320b and 330b may be alleviated. The transparent panel
manufactured by the above-described method may be advantageous when being
applied to a window-integrated touch screen in which the sensing
electrodes 320b and 330b are directly formed on the cover lens 340b.

[0048] FIG. 4 is a flowchart illustrating a method of manufacturing a
transparent panel according to an embodiment of the present invention.

[0049] Referring to FIG. 4, the method of manufacturing the transparent
panel according to the present embodiment initiates with preparing a
transparent substrate (S400). As described above, the transparent
substrate may be an acrylic-based substrate formed of polyethylene
terephthalate (PET), polycarbonate (PC), polyethersulfone (PES),
polyimide (PI), polymethymethacrylate (PMMA) or the like, or a window
substrate formed of tempered glass or the like. A graphene oxide layer is
formed on the transparent substrate (S410).

[0050] The graphene oxide layer may be formed by applying a solution, in
which a solid-type graphite is diluted in water or an organic solvent, to
the transparent substrate by a gravure coating method, a slot die coating
method, a spray coating method or the like. The graphene oxide solution
has excellent dispersibility, and thus it is easy to form the graphene
oxide layer on the transparent substrate. In addition, the graphene oxide
solution has non-electrical conductivity, that is, insulating properties.

[0051] After the graphene oxide layer is formed, an etching resist is
formed on a first area corresponding to at least a portion of the
graphene oxide layer (S420). The etching resist is formed on the first
area of the graphene oxide layer intended to maintain its insulating
properties without being reduced. Also, in order to prevent the first
area from being reduced in the case that the etching resist is affected
by a reducing agent including acid in a subsequent reducing process, the
etching resist may have excellent acid resistance.

[0052] After the etching resist is formed on the first area of the
graphene oxide layer, a second area, on which the etching resist is not
formed, is reduced (S430). A gaseous or liquid reducing agent may be used
in the reducing process, and as described above, at least one of iodic
acid (HI), ammonia (NH3), sodium hydroxide (NaOH), potassium
hydroxide (KOH), hydrogen sulfide, hydrazine, and aluminum powder may be
used therefor. When the reducing process is completed, the etching resist
is removed (S440), and the manufacturing process of the transparent panel
is completed.

[0053] After the above-described operations, the first area of the
graphene oxide layer maintains the insulating properties of the graphene
oxide, and only the second area is reduced to obtain electrical
conductivity. Thus, a transparent electrode may be formed on the
transparent substrate without a thickness difference or a step, and in
particular, when the transparent panel is applied to a window-integrated
touch screen in which a transparent substrate is directly used as a cover
lens, a pattern exposure phenomenon may be minimized.

[0054] FIG. 5 is a schematic view for explaining a method of manufacturing
a transparent panel according to an embodiment of the present invention.

[0055] Referring to FIG. 5, a transparent substrate 510 is prepared, and a
graphene oxide layer 520 is formed thereon using a graphene oxide
solution. As described above with reference to FIG. 4, the graphene oxide
layer 520 may be formed by a gravure coating method, a slot die coating
method, a spray coating method or the like. When the graphene oxide layer
520 is formed and the shape of transparent electrodes and an area in
which the transparent electrodes are to be formed are specified on the
graphene oxide layer 520, an etching resist 530 is formed on a first area
of the graphene oxide layer 520.

[0056] The first area of the graphene oxide layer 520, on which the
etching resist 530 is formed, corresponds to an area excepting for the
transparent electrodes, the area in which the properties of a graphene
oxide having non-electrical conductivity are maintained. When the
graphene oxide layer 520 having the etching resist 530 formed thereon is
reduced, only a second area 525 of the graphene oxide layer 520, which is
not blocked by the etching resist 530 from being in contact with a
reducing agent, is reduced to thereby obtain electrical conductivity.

[0057] After the reducing process, the etching resist 530 is removed to
complete the manufacturing process of the transparent panel. As shown in
FIG. 5, the first area 520 having non-electrical conductivity and the
second area 525 having electrical conductivity of the graphene oxide
layer 520 have the same thickness without a step. Accordingly, unlike
general transparent panels formed by sputtering and etching, a difference
in refractive indices of the transparent substrate 510 and the sensing
electrode 525 does not affect visibility of the sensing electrode 525,
and thus the pattern exposure phenomenon of the sensing electrode 525 may
be minimized.

[0058] As set forth above, according to embodiments of the present
invention, a graphene oxide layer is formed on at least a surface of a
transparent substrate, and the graphene oxide layer includes a first area
having non-electrical conductivity and a second area having electrical
conductivity. Thus, a transparent electrode may be formed without a step,
whereby a pattern exposure phenomenon may be alleviated while the
manufacturing process of a transparent panel may be simplified.

[0059] While the present invention has been shown and described in
connection with the exemplary embodiments, it will be apparent to those
skilled in the art that modifications and variations can be made without
departing from the spirit and scope of the invention as defined by the
appended claims.

Patent applications by Kang Heon Hur, Seongnam KR

Patent applications by Kyu Sang Lee, Suwon KR

Patent applications by Woon Chun Kim, Suwon KR

Patent applications by Samsung Electro-Mechanics Co., Ltd.

Patent applications in class Including components having same physical characteristic in differing degree

Patent applications in all subclasses Including components having same physical characteristic in differing degree